Meyron

Reference summary — not medical advice or a personal risk estimate.

Opisthorchis viverrini

Group 1 — carcinogenic to humansInfectionsbiologicalEvidence: sufficient_in_humans

Quick answer

Classified as Group 1 — carcinogenic to humans, based on sufficient evidence in humans. Infection. Caught from eating raw or undercooked freshwater fish in parts of Southeast Asia. Treatable with antiparasitic drugs.

Summary

A liver fluke from undercooked freshwater fish in Southeast Asia. Associated with bile duct cancer.

Detail

Opisthorchis viverrini is Group 1 with sufficient evidence for cholangiocarcinoma (bile duct cancer). Infection comes from eating raw or undercooked freshwater fish carrying the larvae. Antiparasitic drugs treat infection.

What's not established

This classification is based on sufficient evidence in humans that this factor can cause cancer. It does not establish a safe exposure threshold, your personal risk, or how this factor's risk compares in size to other Group 1 agents — hazard classifications are not ranked by magnitude.

Regional relevance

southeast_asia

regional

Evidence sources

Every claim on this page traces back to one of these. Click through to read the primary document yourself.

Primary sources

NCI

NCI — Risk Factors: Infectious Agents

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IARC

IARC Monographs — Classifications by Cancer Site, Vols 1–140

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Supporting sources

ECDC

ECDC — Communicable diseases and cancer risk (European Centre for Disease Prevention and Control)

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ACS

ACS — Known and Probable Human Carcinogens

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NTP

NTP — Report on Carcinogens (US National Toxicology Program)

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Last reviewed: October 2026

Official reference list

A government list some readers use alongside the primary evidence. Meyron is not affiliated with it. A chemical being listed does not by itself describe a risk from any particular product.